2005-04-16 18:20:36 -04:00
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#ifndef _ASM_GENERIC_PGTABLE_H
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#define _ASM_GENERIC_PGTABLE_H
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2006-09-26 02:32:29 -04:00
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#ifndef __ASSEMBLY__
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2007-08-10 16:01:20 -04:00
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#ifdef CONFIG_MMU
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2006-09-26 02:32:29 -04:00
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2005-04-16 18:20:36 -04:00
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#ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
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/*
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* Largely same as above, but only sets the access flags (dirty,
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* accessed, and writable). Furthermore, we know it always gets set
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* to a "more permissive" setting, which allows most architectures
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2007-06-16 13:16:12 -04:00
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* to optimize this. We return whether the PTE actually changed, which
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* in turn instructs the caller to do things like update__mmu_cache.
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* This used to be done in the caller, but sparc needs minor faults to
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* force that call on sun4c so we changed this macro slightly
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2005-04-16 18:20:36 -04:00
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*/
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#define ptep_set_access_flags(__vma, __address, __ptep, __entry, __dirty) \
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2007-06-16 13:16:12 -04:00
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({ \
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int __changed = !pte_same(*(__ptep), __entry); \
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if (__changed) { \
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set_pte_at((__vma)->vm_mm, (__address), __ptep, __entry); \
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flush_tlb_page(__vma, __address); \
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} \
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__changed; \
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})
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2005-04-16 18:20:36 -04:00
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#endif
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#ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
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#define ptep_test_and_clear_young(__vma, __address, __ptep) \
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({ \
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pte_t __pte = *(__ptep); \
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int r = 1; \
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if (!pte_young(__pte)) \
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r = 0; \
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else \
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set_pte_at((__vma)->vm_mm, (__address), \
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(__ptep), pte_mkold(__pte)); \
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r; \
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})
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#endif
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#ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
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#define ptep_clear_flush_young(__vma, __address, __ptep) \
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({ \
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int __young; \
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__young = ptep_test_and_clear_young(__vma, __address, __ptep); \
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if (__young) \
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flush_tlb_page(__vma, __address); \
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__young; \
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})
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#endif
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#ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR
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#define ptep_get_and_clear(__mm, __address, __ptep) \
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({ \
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pte_t __pte = *(__ptep); \
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pte_clear((__mm), (__address), (__ptep)); \
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__pte; \
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})
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#endif
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[PATCH] x86: ptep_clear optimization
Add a new accessor for PTEs, which passes the full hint from the mmu_gather
struct; this allows architectures with hardware pagetables to optimize away
atomic PTE operations when destroying an address space. Removing the
locked operation should allow better pipelining of memory access in this
loop. I measured an average savings of 30-35 cycles per zap_pte_range on
the first 500 destructions on Pentium-M, but I believe the optimization
would win more on older processors which still assert the bus lock on xchg
for an exclusive cacheline.
Update: I made some new measurements, and this saves exactly 26 cycles over
ptep_get_and_clear on Pentium M. On P4, with a PAE kernel, this saves 180
cycles per ptep_get_and_clear, for a whopping 92160 cycles savings for a
full address space destruction.
pte_clear_full is not yet used, but is provided for future optimizations
(in particular, when running inside of a hypervisor that queues page table
updates, the full hint allows us to avoid queueing unnecessary page table
update for an address space in the process of being destroyed.
This is not a huge win, but it does help a bit, and sets the stage for
further hypervisor optimization of the mm layer on all architectures.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Cc: Christoph Lameter <christoph@lameter.com>
Cc: <linux-mm@kvack.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-03 18:55:04 -04:00
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#ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL
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#define ptep_get_and_clear_full(__mm, __address, __ptep, __full) \
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({ \
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pte_t __pte; \
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__pte = ptep_get_and_clear((__mm), (__address), (__ptep)); \
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__pte; \
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})
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#endif
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2006-10-01 02:29:31 -04:00
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/*
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* Some architectures may be able to avoid expensive synchronization
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* primitives when modifications are made to PTE's which are already
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* not present, or in the process of an address space destruction.
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*/
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#ifndef __HAVE_ARCH_PTE_CLEAR_NOT_PRESENT_FULL
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#define pte_clear_not_present_full(__mm, __address, __ptep, __full) \
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[PATCH] x86: ptep_clear optimization
Add a new accessor for PTEs, which passes the full hint from the mmu_gather
struct; this allows architectures with hardware pagetables to optimize away
atomic PTE operations when destroying an address space. Removing the
locked operation should allow better pipelining of memory access in this
loop. I measured an average savings of 30-35 cycles per zap_pte_range on
the first 500 destructions on Pentium-M, but I believe the optimization
would win more on older processors which still assert the bus lock on xchg
for an exclusive cacheline.
Update: I made some new measurements, and this saves exactly 26 cycles over
ptep_get_and_clear on Pentium M. On P4, with a PAE kernel, this saves 180
cycles per ptep_get_and_clear, for a whopping 92160 cycles savings for a
full address space destruction.
pte_clear_full is not yet used, but is provided for future optimizations
(in particular, when running inside of a hypervisor that queues page table
updates, the full hint allows us to avoid queueing unnecessary page table
update for an address space in the process of being destroyed.
This is not a huge win, but it does help a bit, and sets the stage for
further hypervisor optimization of the mm layer on all architectures.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Cc: Christoph Lameter <christoph@lameter.com>
Cc: <linux-mm@kvack.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-03 18:55:04 -04:00
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do { \
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pte_clear((__mm), (__address), (__ptep)); \
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} while (0)
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#endif
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2005-04-16 18:20:36 -04:00
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#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH
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#define ptep_clear_flush(__vma, __address, __ptep) \
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({ \
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pte_t __pte; \
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__pte = ptep_get_and_clear((__vma)->vm_mm, __address, __ptep); \
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flush_tlb_page(__vma, __address); \
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__pte; \
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})
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#endif
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#ifndef __HAVE_ARCH_PTEP_SET_WRPROTECT
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2005-11-07 03:59:43 -05:00
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struct mm_struct;
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2005-04-16 18:20:36 -04:00
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static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long address, pte_t *ptep)
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{
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pte_t old_pte = *ptep;
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set_pte_at(mm, address, ptep, pte_wrprotect(old_pte));
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}
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#endif
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#ifndef __HAVE_ARCH_PTE_SAME
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#define pte_same(A,B) (pte_val(A) == pte_val(B))
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#endif
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2007-04-27 10:01:57 -04:00
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#ifndef __HAVE_ARCH_PAGE_TEST_DIRTY
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#define page_test_dirty(page) (0)
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#endif
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#ifndef __HAVE_ARCH_PAGE_CLEAR_DIRTY
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#define page_clear_dirty(page) do { } while (0)
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#endif
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#ifndef __HAVE_ARCH_PAGE_TEST_DIRTY
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2005-06-21 20:15:13 -04:00
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#define pte_maybe_dirty(pte) pte_dirty(pte)
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#else
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#define pte_maybe_dirty(pte) (1)
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2005-04-16 18:20:36 -04:00
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#endif
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#ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_YOUNG
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#define page_test_and_clear_young(page) (0)
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#endif
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#ifndef __HAVE_ARCH_PGD_OFFSET_GATE
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#define pgd_offset_gate(mm, addr) pgd_offset(mm, addr)
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#endif
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#ifndef __HAVE_ARCH_LAZY_MMU_PROT_UPDATE
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#define lazy_mmu_prot_update(pte) do { } while (0)
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#endif
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2006-06-01 20:47:25 -04:00
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#ifndef __HAVE_ARCH_MOVE_PTE
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2005-09-28 00:45:18 -04:00
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#define move_pte(pte, prot, old_addr, new_addr) (pte)
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#endif
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2005-04-16 18:20:36 -04:00
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/*
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2005-04-19 16:29:17 -04:00
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* When walking page tables, get the address of the next boundary,
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* or the end address of the range if that comes earlier. Although no
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* vma end wraps to 0, rounded up __boundary may wrap to 0 throughout.
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2005-04-16 18:20:36 -04:00
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*/
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#define pgd_addr_end(addr, end) \
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({ unsigned long __boundary = ((addr) + PGDIR_SIZE) & PGDIR_MASK; \
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(__boundary - 1 < (end) - 1)? __boundary: (end); \
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})
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#ifndef pud_addr_end
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#define pud_addr_end(addr, end) \
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({ unsigned long __boundary = ((addr) + PUD_SIZE) & PUD_MASK; \
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(__boundary - 1 < (end) - 1)? __boundary: (end); \
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})
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#endif
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#ifndef pmd_addr_end
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#define pmd_addr_end(addr, end) \
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({ unsigned long __boundary = ((addr) + PMD_SIZE) & PMD_MASK; \
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(__boundary - 1 < (end) - 1)? __boundary: (end); \
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})
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#endif
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/*
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* When walking page tables, we usually want to skip any p?d_none entries;
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* and any p?d_bad entries - reporting the error before resetting to none.
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* Do the tests inline, but report and clear the bad entry in mm/memory.c.
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*/
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void pgd_clear_bad(pgd_t *);
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void pud_clear_bad(pud_t *);
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void pmd_clear_bad(pmd_t *);
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static inline int pgd_none_or_clear_bad(pgd_t *pgd)
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{
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if (pgd_none(*pgd))
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return 1;
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if (unlikely(pgd_bad(*pgd))) {
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pgd_clear_bad(pgd);
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return 1;
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}
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return 0;
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}
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static inline int pud_none_or_clear_bad(pud_t *pud)
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{
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if (pud_none(*pud))
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return 1;
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if (unlikely(pud_bad(*pud))) {
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pud_clear_bad(pud);
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return 1;
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}
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return 0;
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}
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static inline int pmd_none_or_clear_bad(pmd_t *pmd)
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{
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if (pmd_none(*pmd))
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return 1;
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if (unlikely(pmd_bad(*pmd))) {
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pmd_clear_bad(pmd);
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return 1;
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}
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return 0;
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}
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2007-08-10 16:01:20 -04:00
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#endif /* CONFIG_MMU */
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/*
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* A facility to provide lazy MMU batching. This allows PTE updates and
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* page invalidations to be delayed until a call to leave lazy MMU mode
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* is issued. Some architectures may benefit from doing this, and it is
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* beneficial for both shadow and direct mode hypervisors, which may batch
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* the PTE updates which happen during this window. Note that using this
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* interface requires that read hazards be removed from the code. A read
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* hazard could result in the direct mode hypervisor case, since the actual
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* write to the page tables may not yet have taken place, so reads though
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* a raw PTE pointer after it has been modified are not guaranteed to be
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* up to date. This mode can only be entered and left under the protection of
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* the page table locks for all page tables which may be modified. In the UP
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* case, this is required so that preemption is disabled, and in the SMP case,
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* it must synchronize the delayed page table writes properly on other CPUs.
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*/
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#ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE
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#define arch_enter_lazy_mmu_mode() do {} while (0)
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#define arch_leave_lazy_mmu_mode() do {} while (0)
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#define arch_flush_lazy_mmu_mode() do {} while (0)
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#endif
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/*
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* A facility to provide batching of the reload of page tables with the
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* actual context switch code for paravirtualized guests. By convention,
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* only one of the lazy modes (CPU, MMU) should be active at any given
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* time, entry should never be nested, and entry and exits should always
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* be paired. This is for sanity of maintaining and reasoning about the
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* kernel code.
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*/
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#ifndef __HAVE_ARCH_ENTER_LAZY_CPU_MODE
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#define arch_enter_lazy_cpu_mode() do {} while (0)
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#define arch_leave_lazy_cpu_mode() do {} while (0)
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#define arch_flush_lazy_cpu_mode() do {} while (0)
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#endif
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2005-04-16 18:20:36 -04:00
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#endif /* !__ASSEMBLY__ */
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#endif /* _ASM_GENERIC_PGTABLE_H */
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